The following background information may present examples of specific aspects of the prior art (e.g., without limitation, approaches, facts, or common wisdom) that, while expected to be helpful to further educate the reader as to additional aspects of the prior art, is not to be construed as limiting the present invention, or any embodiments thereof, to anything stated or implied therein or inferred thereupon. Electronic controlled antiskid systems may be found on many wheeled vehicles including, but not limited to, most cars, large airplanes and some motorcycles. These vehicles typically have powered hydraulic or pneumatic brake systems that work in conjunction with the antiskid system. These electronic controlled antiskid systems generally use wheel speed sensors, an electronic controller and control valves to regulate the brake pressure in the powered brake systems to reduce tire skids. These electronic controlled antiskid systems can increase safety by improving directional control and shortening the stopping distance of the vehicle by reducing tire skids when braking. These electronic controlled antiskid systems are also referred to as Antilock Brake Systems (ABS).
Manual brake systems typically use the force from an operator's feet and/or hands to provide the energy to actuate and power hydraulic or mechanical brakes. These vehicles generally do not have powered hydraulic or pneumatic brakes. Examples of wheeled vehicles with manual brakes include, without limitation, general aviation aircraft, motorcycles, and bicycles. Although there are a large number of vehicles with manual brakes that may benefit from an electronic controlled antiskid system, to date it is believed that there are few if any practical electronic controlled antiskid systems available for these vehicles. Many electronic controlled antiskid systems in use today on wheeled vehicles require a powered hydraulic or pneumatic brake system for their operation. Power for these brake systems is generally provided from a hydraulic or pneumatic pump coupled to the vehicle's engine or an electric motor that its powered by the vehicle's electrical system.
The following is an example of a specific aspect in the prior art that, while expected to be helpful to further educate the reader as to additional aspects of the prior art, is not to be construed as limiting the present invention, or any embodiments thereof, to anything stated or implied therein or inferred thereupon. FIG. 1 is a schematic diagram showing a powered hydraulic brake system with an electronic controlled antiskid system for an aircraft with two main wheels 115, in accordance with the prior art. Hydraulic fluid is directed from a reservoir 100 to a hydraulic pump 102 via a hydraulic pipe 101. Pump 102 is driven by a vehicle engine 103 or an electric motor 104 that is powered by the vehicle's electrical system. Hydraulic fluid is directed from pump 102 through a hydraulic pipe 105 to a relief valve 106 that ensures that the maximum hydraulic system pressure is not exceeded. The hydraulic fluid is directed to left and right metering valves 108 through hydraulic pipes 107.
An aircraft brake system allows the pilot to apply the brakes independently to left and right main wheels 115 by pressing on left and right brake pedals 109. Left and right brake pedals 109 are connected to their respective metering valves 108. When the pilot pushes on brake pedals 109, metering valves 108 modulate the pressure of the hydraulic fluid through pipes 110 to brake cylinders 111. Brake pistons 112 inside brake cylinders 111 are connected to brake pads 113. When the pilot pushes on brake pedals 109, brake cylinders 111 cause brake pads 113 to push against brake discs/drums 114 creating the friction to slow the turning brake discs/drums 114 that are connected to wheels 115. This action slows or stops the aircraft. A back up system is required for some vehicles so they can be stopped if there is a loss of power to the brake system. On a powered hydraulic brake system, this can be accomplished by adding a hydraulic accumulator 124 to the brake system.
The electronic controlled antiskid system needs to monitor the rotation of wheels 115 to determine when a skid is occurring or about to occur. This is done with wheel speed sensors 116 located at each wheel 115. A tone ring 117 turns with wheel 115 and creates a magnetic field disruption that can be detected by wheel speed sensors 116. Wheel speed sensor 116 and tone ring 117 are typically integrated into a single unit and located inside the axle on large aircraft. The wheel speed signals are sent to an electronic controller 119 using electrical cables 118. Using the speeds from wheel speed sensors 116, electronic controller 119 determines when a skid condition is occurring and sends a signal to required control valves 122 through electrical cables 120 to reduce the brake pressure. Hydraulic fluid is released from brake cylinders 111 through pipes 121, through control valves 122 and through pipes 123 back to reservoir 100. When controller 119 determines that the skid event is over, it commands required control valves 122 to close, and the brake system returns to its normal braking mode.
FIGS. 2A and 2B illustrate manual brake systems, according to the prior art. FIG. 2A is a schematic diagram showing a manual hydraulic brake system for a general aviation aircraft, and FIG. 2B is a schematic diagram showing a manual mechanical brake system for a motorcycle or bicycle. Manual brake systems use the force from the operator's feet and/or hands to provide the energy to actuate and power the hydraulic or mechanical brakes. Manual hydraulic brake systems are common on general aviation aircraft, motorcycles, and bicycles. These vehicles do not have powered hydraulic or pneumatic brakes. These vehicles use a separate hand or foot lever for each wheel that has a brake.
Referring to FIG. 2A, a manual hydraulic brake system for a right main wheel 115 is shown for a general aviation (GA) aircraft. There is also a duplicate manual hydraulic brake system for the left main wheel on the GA aircraft. The pilot provides the power for the actuation of the brakes by pushing on a brake pedal 200 with his foot. Brake pedal 200 is coupled to an input shaft 201 that is inserted into a hydraulic master cylinder 202. Input shaft 201 is connected to a master cylinder piston 203 located inside master cylinder 202. When the pilot pushes on brake pedal 200, hydraulic fluid is moved out of master cylinder 202 and into a brake pipe 204 that is connected to a brake cylinder 111. Fluid in brake pipe 204 is pushed into brake cylinder 111 thus moving a brake piston 112. Brake piston 112 is connected to a brake pad 113, which is pushed against a brake disc/drum 114 creating the friction to slow the turning brake disc/drum 114 that is connected to wheel 115. This action slows or stops the aircraft.
Manual mechanical brake systems are common on motorcycles and bicycles. These vehicles use a separate hand and/or foot lever for the front and rear wheels, which each have a brake. Referring to FIG. 2B, a manual mechanical brake system for a motorcycle or bicycle is shown. Only the brake system for the rear wheel is shown. There is normally a manual mechanical brake system for the front wheel as well on motorcycles and bicycles. The vehicle operator provides the power for the actuation of the brakes by pushing or pulling on a brake lever 200 with his hand and/or foot. Brake lever 200 is coupled to a mechanical lever 206 with a rod or cable 205. When the operator pushes or pulls on brake lever 200, mechanical lever 206 pulls or pushes on a rod or cable 207 that is connected to a mechanical lever 208 that is connected to a brake pad 113, which is pushed against a brake disc/drum 114 creating the friction to slow the turning brake disc/drum 114 that is connected to a wheel 115. This action slows or stops the vehicle. The number and arrangement of rods, cables and levers in different manual mechanical brake systems varies depending on the geometry of the vehicle.
Hybrid manual brake systems exist that combine hydraulic and mechanical linkages to couple the operator's hand and/or foot movements to operate and power the brake mechanism. The brake pads in these hybrid manual brake systems can be mechanically or hydraulically actuated.
By way of educational background, another aspect of the prior art generally useful to be aware of is that there are currently known electronically controlled antiskid systems for manual hydraulic brake systems for motorcycles. As illustrated by way of example in FIG. 1, it is believed that today's electronically controlled antiskid systems are not well suited for vehicles with manual brakes since a power source for the brake system must be added to the vehicle. Due to the added weight and cost and the difficulty of mounting the many needed components, one may expect that an electronically controlled antiskid system is typically not practical for these types of vehicles. There are some currently known mechanical antiskid devices, not systems, for bicycles with manual brakes. However, it is believed that these mechanical devices offer reduced antiskid performance when compared to electronically controlled antiskid devices.
In view of the foregoing, it is clear that these traditional techniques are not perfect and leave room for more optimal approaches.